Process and apparatus for wood distillation.



P. WUIDIGH.

PROCESS MID APPARATUS FOR WOOD DISTILLATIONBI APPLIOATIOE FILED OU'LB,1912.

Patsngevi Apr. '7, 19714.

2 QHEETS-SKEET 1.

a .w/ //V/ F. WOIDICH. PROOESS AND APPARATUS FOR W001 DISTILLATION.APPLICATION FILED 0093.8, 1912. Q

\ 1 092;620 Patented Apr, 7, 1914.

2 SHEETS-SEEK?) 2.

To all 4.071 am it may concern UNITED STATES PATENT'QEFFIQE,

FRANZ WOIDICH, OF PRAGUE- WEINBERGE, AUSTRIA-HUNGARY.

PROCESS AND APPARATUS FOR WOOD DISIILLATION.

M Specification of Letters Eatent.

/1 Application filed October 8, 1912. Serial-Ho. 724,584.

and oily constituents that the other products, such asacetic acid, woodalcohol, etc., may

be successively recovered free from contamination by tar or oils, theseproducts being thus directly produced in a state of commercial purity.

1 In the destructive distillation of wood, the gases and vapors arenotproduced at a uniform rate and the composition of such gases and vaporsvaries during the progress of the distillation. Owing to thesevariations in volume and composition, the cooling of the current ofmixed gases and vapors to a temperature suiiicient to condense the tardoes not insure a clean separation between the tar and oils on the onehand, and the acid vapors on the other. The tar, thus separated, retainsa greater or percent. of acetic acid; and the acid vapors carry alongtarry and oily constituents which contaminate the products, such asacetic acid and wood alcohol, condensed from such vapors. llVood tar, asis well known, contains heavy and light oils, the heavier oils having ahigher boiling point thin the lighter oils (see Industrial (7/tcmz'stry,1ilogers and iltu-bert, pages 5 10, 541). It is these oils of lowerboiling point which are inost likely to escape condensation,

' and it is the object of my invention to provide a process whereby thisdifiiculty obviated, and whereby there may be effected the completeseparation from the distilla' tion gases of the tars and oilscommercially free from acid, as well as a dircct and continuousproduction of commercially good qualities of acetate (gray acetate oflime exceeding 80 per cent!) and wood alcohol, at any stage of the wooddistillation process,

Referring .to' the drawings, Figure l is an elevation of the plant; Fig.2 is a plan of Fig. 1; Fig. 3 is asection of the tar purii ficationportion of the plant; and Fig.4 is a plan of the mixing'head and itsconnections Referring to Figs. 1 and 2, A, A, A, A, are a series of wooddistilling ovens from which the distillation gases and vapors passthrough pipes 1, 2, into a collecting main 3. The ends of the pipes 2open into'the main Patented Apr, 7, 1914.

3 to permit the distillation gases to flow over the ta in the main.

4 is a pipe through which tar is delivered into the main 3- from a pump5, connected by pipe 6 to the tar separator. The gases pass through thepipe 7 into the top of the column 8, thence through one of pipes 9 intothe tar separator 1) (two being shown for alternate or simultaneous use)from which the tar-freed gases are delivered to pipe 11, and thencethrough the apparatus for recovering acetic acid, wood alcohol, etc., toa suction pump (not shown) from which the Waste gases aredeliveredeither directly or through the heat interchanger (to .be laterdescribed) ,to the combustion fur naces for heating the wood-distillingretorts. The tar, dcliverd from pipe 4 into the main 3, as well as that.which separates from the distillation gases, flows downwardly in themain 3, from which his delivered into the tar. collector 12, andjthencethrough pipe 13 into the column 8. By an additional valved .pipe 14:,the tar may be delivered into the bottom of the column-8, for a 'purposeto'be later'referred to.

X is a valved pipe to permit exhaust o vapors directly to the outer airin case of necessity.

Referring now Figs. 3 and 4, it will be noted that the delivery pipe 7leads into a mixing-head 15, atthe top of the column 8. Below thismixing head 15, is arranged a heat-interchanger B, which may be of anysuitable construction, As shown, it consists of a series of tubes 16,through which the distillation gases pass, the tubes passing through aseries or staggered partitions 17. A cooling fluid surrounds the pipes,either cool waste gases or water being used. The

tom of the heat interchanger B through pipe 191 and exhausted at the topthrough pipe 18.

If water is used as the cooling agent, it is admitted through pipe 20 atthe bottom of the heat interchanger B and exhausted at the top throughpipe 19. If Waste gases are used, they are heated and then burned toheat the retorts; Below the heat=inte-ror filter 21, to separate out'anysolid maof tar through the perforation.

4 plate 71 up changer B is arranged a cataract for ntimately mixing thedistillation gases with tar, the cataract being designated as a Whole bvthe letter C.

The tar from .the collecting main 3 flows through pipe 21, into thetar-collector 12, which is provided wlth a transverse screen terialssuch as coke, etc. The tar entering the column through pipe 13, flowsonto the upper one of a sieries of perforated plates 22. Each of these pates 522 has a dam 24 around the perforation; and the dam 24 of theuppermost plate has a perforated upward extension or screen23, oppositethe opening of the pipe13, to prevent an unequal How The tar rises andflows through the holes in the screen 23 and over the edge of the dam24, and falls onto a plate 25, supported on legs 26, thence splashesover'onto the next plate 22, and is thus brought into a filflelX-dlYldedcondition, while all the, time in intimate contact with thedownwardly-flowing current of distillation gases. Other forms ofcataract device may, of course, be used.

From the bottom of the cataract, the mixed gases and vapors,nowcarr'ying a mist of tar-particles, pass through pipes 9 and'31, intothe main tar separator D.

' Any suitable form of'tar separator may be used, As shown there areprovided a series of centrally arranged inclined plates 70, 70, andannular inclined plates '71. Theincoming stream of mixed gases carryingthe tarry particles strikes the first plate 7 O, and' 'ng laterallyagainst the side of then expand the vessel,}--

pmpelled to pass under the rdly against the plate 70, and so on,tliereby';being subjected to a series of impacts, expansions andcontractions and abrupt changes of direction, whereby the tarryparticles are separated out. The tar flows down the inclined plates andcollects in the space at the bottom of the separator around the pipe 31.The pipe 6 delivers tar to the" tar-pump, and the excess tar iswithdrawn through the pipe 80. An auxiliary tar separator E providedwith similarly arranged inclined shelves, maybe ar-;

ranged above the main separator to rcover 'any residual tar particles.

The exit pipe 11 is provided with a thermometer 4:8, and atest-condenser 49. Other thermometers 50, 51, are provided. at suitablepoints, and glass-covered peepholes, such as 52 in the main separator D,and 81 in the exit pipe 11, nable the operator to observe the conditionot the gases at various points'in the apparatus. In Fig. 4 and the upperleft-hand portion of Fig. 3, a device is shown, at the top of the mixinghead 15 forini roducing fluids.

90, 91, D2 and 93 are valved pipes for water, cool pern'lanent gases,steam and tar thecoolcr or rccuperator B,

- sary to dilute and cool the same, which is effected by introducingsteam, water, or cool inert gases. It may also be necessary to introduceadditional tar through the pipe 93, which is connected to the tar-pump,in case the uantity of tar delivered to the cataract, rom the tarcollector 12, is not sufficient to absorb the tarry vapors in theabnormal quantity of distillation gases.

The process is carried out as follows :-1'n starting the operation, whenno tar is available, the distillation gases are passed through theheat-interchangerB, which is cooled to a point suflicient to condense as'far as possible not only the tar but also the acid and water vapors,with a result that there is delivered into the tar-collecting space ofthe main separator 10, a highly acid tar mixture which 18 by the pumpdelivered into the collecting-main 3 where it is subjected to the highlyheated gasescoming from the wood distilling ovens. The acid and oilyconstituents of the tar are thereby evaporated and again delivered tothe cooler and tar-collector until a suflicient quantity of tar has beencollected to enable the apparatus to operate in the normal manner. Afterthe plant has begun to operate in the normal Way, tar of normalconsistency is delivered by the tarpump 5, through pipe 4, to thegas-collecting main 3, where it is, as above described, brought intointimate contact with the highly heated outgoing current of wooddistillation gases, whereby there are vaporized from the tar the oilyconstituents, so that the distillation gases are completely saturated,under the existing temperature and pressure, with the oil vapors. Thetar in its fiow down the collecting main carries with it all solidmaterial and thus prevents an clogging of this pipe. The saturatedistillation gases are delivered into the mixing head 15, and thence intothe cooler or regenerator B, where the gases are cooled approximately tothe dew-point oi. the high-boiling-poirit vapors. It has been found thatthe vapors of the high-boiling-point ingredients, condensed or partlycondensed to a mist or cloud, have a dissolving or absorbing action onthe vapors of the lower-boiling-point oils, so that. the tendency of thelowcrboilingpointoils to separate from the mixture is greatlydiminished. After passing through the distillation gases, now containinga mist of oih ,and tarry vapors, are brought into intimate con tact withthe oil-:l reed tar which is delivered from the tar-separator ihinJlXiH'ic be ing efi'e rtcd in the catara t amiaratus C,

Its

. liquid, and

especially those of low-boiling point, the

' vapors of which otherwise would escape with the acid vapors throughoutthe subsequent stages of the process. After passing through" thecataract O, the mixture of the distillation gases, oil and tar globulesand vapors, and mechanically entrained tar particles, is-

- delivered through'a pipe to the bottom. of the main tar-separator D,in which andin the auxiliary separator, if used, the tar is, by thesuccessive expansions, contractions, impacts, and changes of directionof the gas,

' completely separated. The mixed gases,

now freed from tar, oil and oily vapors,are delivered to a connectedseries of apparatus in which the acetic acid, Wood alcohol, etc,

are continuously recovered in the usual way.

5 The residual inert gases are delivered to the suction side of a pump(not shown), whence they may be forced, after passing through therecuperator, as above described, into the fire-boxesof the oven-heatingapparatus.

In case the ovens should, for any reason, he overheated, andparticularly at that stage of the distillation when the exothermicreactions begin, there may be evolved from the wood an abnormal quantityof very/dense mixture of gases and vapors, from which the tar and oilswould not be separated by the apparatus operating in the normal. manner.I have accordingly provided at the top of the mixing-head, means fordiluting and i cooling this dense mixture to the desired cnsistency andtemperature. This is effected by introducing. into the gases wetsteam,'a spraygpf water or a current of cool waste gases. The effect ofthe introduction of these additions is 'to so dilute the dense mixturethat its consistency'becomes normal, and also to so cool it as to lowerits temperature to the desired point, so that the partial condensationof the vapors of high-boilingpoint oil and tar vapors is effected, as inthe ordinary operation of the apparatus. In this case the cooler orrecuperator acts most elliciently as a means for insuring a, complete 2/mixture of all the ingredients of the gasmixture.

During the abnormal gas and vapor development additional tar may besupplied to the mixing-head through pipe 93 and the speed of the gas andvapor current is increased by accelerating'the speed of the pump (notshown) which sucks the gases through the system.

The heat interchanger B may be cooled either by water, or preferably maybe used as a recuperator for heating the permanent locatedcollecting-mam.

. acid vapors,

gases remaining after all condensaldc ingredients have been removed,these permanent gases thus being heated prior to their use as fuel forheating the ovens.

, To enable the operator to control the operations of the apparatus, atestcondenser' 49 is provided beyond, the auxiliary separator so that itcan be ascertained by examination of the condensed liquid whether it isor is not free from oil. In the normal operation of the apparatus thethermometer in the tube at the bottom of the cataract should indicateabout 150 to 160 CW Ifthe temperature at this point is correct and'thereis still found to be an incomplete separation of the tar-pump to deliveradditional tar to the By controlling the velocity of the gases and thequantity of tar delivered by the tar-pump, the exact operation of theapparatus can be readily maintamed.

While I have shown a main tar-separator and an auxiliary tar-separator,it is not always in practice necessary to use b 1th of the oil, it isnecessary to cause these devices as either one alone maybe suilicient.

It will be noted that. my process is continuous in operation, 27. a,there is a con tinuous treatment of the distillationgases in a series ofapparatuses by which there is produced a tarcommercially free from acidsor other valuble volatilizable ingredients, and commercially tar-freeacid gases suitable for direct recover-y, without additionaldistillation or purification, of the acetic acid (gray acetate of limeexceeding 80 per cent), wood-alcohol, etc., in a commercially purecondition. There is required, in the recovery of these commercialproducts, no additional heat, the heat remaining in the gases beingsuilicient to enable the well-known recovery-procedure to be effected.

I claim:

1. The process for the separation from the gases and vapors evolvedduring the destructive distillation of wood and other organic materials.of acid-free tar and tar-free which consists in bringing liquid tar intocontact with the hot gases leaving'the ovens whereby the oilyconstituents of the tar are vaporized and the hot gases saturated withoil vapors, separating the liquid tar from the gas current, lowering thetemperature of the gases to the dewpoint of the higher-boiling-pointoily con-- bringing into intimate stituent. then again contact thedistillation gases and the tar from which the oily constituentshad'previouslv been removed, and then separating the tar from the gases.1

' 2. The process of treating the gases and vapors evolved during wooddistillation, which consists in saturating the hot gases with tar-oilvapors, lowering the temperature of the'gascs to the dcw-point of thehighc='-boiling-point oil constituent, then bringing into intimatecontact the thus treated gas with oil-free tar, whereby the tar ahsorhsor dissolves the oily constituents, and

then separating the tar from the gases.

3. The process of treating the gases and vapors evolved during Wooddistillation, which consists in saturating the hot gases with tar'oi]vapors, lowering the temperature of the to the dew-point of thehigher-hoiling-point oil constituent, then bringing into intimatecontact the thus heated gas with oil-tfree tar, whereby the tar absorbsor dissolves the oilyconstituents, and then separating the tar from thegases by subjecting the mixed tar and gas to a suc ccssion of impacts,compressions, expansions, and. abrupt changes of dir tion. I

4. An apparatus comprising a wood-dis tilling oven, a collecting mainfor the gases evolved from such oven, means .for delivering tar intosaid collecting main, a conduit connected to sald collecting main andincluding therein a cooler, a cataract and a tar,-; separator, and aconduit for delivering tar.

from the collecting main to the cataract.

5. An apparatus comprising a xvood-dis -IQ,

tilling oven, a'collecting main for the gases evolved from-such oven,means for delivering tar into said collecting main, a conduit FRANZWOIDICH.

Witnesses:

FUR. JUERGENSEN, J H. BRICKENSTEIN.

